Mental Illness and addiction

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(NC)-Weekend warriors know that it often doesn't help to treat physical ailments in isolation. A jogger with a sore ankle and aching knee, for example, may face recurring injuries if either is treated alone. To get back up and running, both problems need to be treated at the same time. What's more, in some cases both injuries may have a common cause, a cause that may be somewhere else in the body.

In the same way, there's a growing understanding of the close and often intertwined relationship between mental illnesses and addiction. "We've realized that many patients with substance abuse issues have mental health problems, and that people with mental health problems wrestle with substance abuse," says Dr. Usoa Busto, who works at the Center for Addiction and Mental Health in Toronto.

With funding from the Canadian Institutes of Health Research, Busto and a team of researchers are probing into why so many people who have mood disorders are also addicted to alcohol, nicotine, or gambling. "If we can understand the mechanisms then it could have major implications for treatment," says Busto.

Previous research strongly suggests a connection between addiction and mental illness. For example, alcohol use disorders are nine times more prevalent in patients with bipolar disorder than in the general population, and are also associated with higher suicide rates. The prevalence of nicotine and alcohol use disorders are two to four times higher in patients with mental health disorders than in the general population.

Busto's team has found that people with mental illnesses and an addiction may have lower than normal levels of dopamine, an important neurotransmitter in the brain. The finding may have implications for treatment of both disorders. For example, while many of the newer antidepressant drugs boost serotonin levels, treatment using specific drugs that also increase dopamine into the system might not only be more effective at treating depression it may also attack the underlying causes of the addiction.

Busto is also looking for common genetic variations shared by people with tobacco or alcohol addictions who also have a mood disorder, work that may prove useful for disease prevention and detection, says Busto. "People with the specific mutation in the gene, for example, might be warned that they need to be careful because they may be more prone to alcoholism or depression."

While the research is still in its infancy, Busto is enthusiastic at the possibilities for both prevention and treatment. "Not only may we be able to use better treatments to deal with a patient's mood disorder and substance abuse, we may even be able to prevent their occurrence."